Blood and saliva SARS-CoV-2 antibody levels in self-collected dried spot samples

Laura Lahdentausta*, Anne Kivimäki, Lotta Oksanen, Marika Tallgren, Sampo Oksanen, Enni Sanmark, Aino Salminen, Ahmed Geneid, Mikko Sairanen, Susanna Paju, Kalle Saksela, Pirkko Pussinen, Milla Pietiäinen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
39 Downloads (Pure)


We examined the usefulness of dried spot blood and saliva samples in SARS-CoV-2 antibody analyses. We analyzed 1231 self-collected dried spot blood and saliva samples from healthcare workers. Participants filled in a questionnaire on their COVID-19 exposures, infections, and vaccinations. Anti-SARS-CoV-2 IgG, IgA, and IgM levels were determined from both samples using the GSP/DELFIA method. The level of exposure was the strongest determinant of all blood antibody classes and saliva IgG, increasing as follows: (1) no exposure (healthy, non-vaccinated), (2) exposed, (3) former COVID-19 infection, (4) one vaccination, (5) two vaccinations, and (6) vaccination and former infection. While the blood IgG assay had a 99.5% sensitivity and 75.3% specificity to distinguish participants with two vaccinations from all other types of exposure, the corresponding percentages for saliva IgG were 85.3% and 65.7%. Both blood and saliva IgG-seropositivity proportions followed similar trends to the exposures reported in the questionnaires. Self-collected dry blood and saliva spot samples combined with the GSP/DELFIA technique comprise a valuable tool to investigate an individual’s immune response to SARS-CoV-2 exposure or vaccination. Saliva IgG has high potential to monitor vaccination response wane, since the sample is non-invasive and easy to collect.

Original languageEnglish
Pages (from-to)173-183
Number of pages11
JournalMedical Microbiology and Immunology
Issue number4
Publication statusPublished - Aug 2022
MoE publication typeA1 Journal article-refereed


  • Antibody
  • Blood
  • COVID-19
  • Dried spot sample
  • Exposure
  • Saliva
  • SARS-CoV-2
  • Vaccination


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